摘要: 基本公式: $$\binom n m = \binom n {n - m}\\ \sum_{i = 0}^n \binom n i = 2 ^ n\\ \binom n m = \binom {n - 1} {m - 1} + \binom {n - 1}{m}$$ 上指标求和: $$\sum_{i 阅读全文
posted @ 2021-10-05 20:21 zzt1208 阅读(116) 评论(0) 推荐(0) 编辑